#define _CRT_SECURE_NO_WARNINGS 1
int tribonacci(int n) {
	int a = 0, b = 1, c = 1, d = 2;
	if (n == 0)
		return 0;
	if (n == 1 || n == 2)
		return 1;
	for (int i = 3; i <= n; i++)
	{
		d = a + b + c;
		a = b, b = c, c = d;
	}
	return d;
}